I think you are misinterpreting the close reason. Opinions are still opinions, even if they come from experts. I'm not sure how "I would like to hear about the Pros/cons of how the tables are laid out and how the data is separated or normalized, and whether or not it might be worth re-structuring." could be construed as not asking for opinions.
However, as for suggestions:
If and only if you can restructure your question to include hard requirements (e.g. how many users are you expecting, what kinds of queries are you running, what kind of information are you trying to represent, what is your current actual design strategy and why do you feel it is inadequate), you may be able to get advice on http://dba.stackexchange.com.
You could go one step further, run some tests and identify specific areas of bottlenecks. Attempt to optimize those bottlenecks, show your attempts, then again, http://dba.stackexchange.com, or perhaps here on http://stackoverflow.com if it is a concrete issue with a specific query rather than a design issue.
In any case, as it stands, you are simply asking for pros and cons of possible approaches. Whether or not the answers come from experts, there will still be experts with differing opinions on the matter. Questions like this do not always have the hard concrete answers that you want them to have. That's why experts are experts; they've had plenty of experience with which to form their opinions, and you are fairly explicitly asking for those opinions.
Responding to your comment below, where you write:
questions like this do not have hard concrete answers. therefore, the only way to get a close enough "definitive" answer would probably be to "ask an expert for his 'opinion'" on the matter no?
That is correct. And SO is categorically not the place to do that. There are other forums that may be more appropriate, e.g. http://www.dbforums.com/ (or wherever, that was just a cursory Google search).
StackExchange sites simply do not exist for that type of question. We never made any claims otherwise. As an analogy, you cannot ask a question about cooking on a home-improvement site then be surprised when your question is rejected, no matter how good/bad of a question it may be (and that also does not imply a problem with the home-improvement site).
I had a few of my first questions here closed as opinion-based as well, and it does sting, but over time I learned what SE is all about.
Check out Having a bad start. Is that normal? for both a good general response to some of your fundamental issues (possibly), and, more importantly, a great example of a constructive way to post about these types of things on meta.